title: Effect of pursed-lip breathing in patients with COPD: Linear and nonlinear analysis of cardiac autonomic modulation.
abstract: OBJECTIVE
  The aim of the present study was to evaluate the effect of pursed-lip breathing (PLB) on cardiac autonomic modulation in individuals with chronic obstructive pulmonary disease (COPD) while at rest.
  
  
  METHODS
  Thirty-two individuals were allocated to one of two groups: COPD (n = 17; 67.29 ± 6.87 years of age) and control (n = 15; 63.2 ± 7.96 years of age). The groups were submitted to a two-stage experimental protocol. The first stage consisted of the characterization of the sample and spirometry. The second stage comprised the analysis of cardiac autonomic modulation through the recording of R-R intervals. This analysis was performed using both nonlinear and linear heart rate variability (HRV). In the statistical analysis, the level of significance was set to 5% (p ≤ 0.05).
  
  
  RESULTS
  PLB promoted significant increases in the SD1, SD2, RMSSD and LF (ms(2)) indices as well as an increase in α1 and a reduction in α2 in the COPD group. A greater dispersion of points on the Poincaré plots was also observed. The magnitude of the changes produced by PLB differed between groups.
  
  
  CONCLUSIONS
  PLB led to a loss of fractal correlation properties of heart rate in the direction of linearity in patients with COPD as well as an increase in vagal activity and impact on the spectral analysis. The difference in the magnitude of the changes produced by PLB between groups may be related to the presence of the disease and alterations in the respiration rate.
authors.affiliation: 1Faculdade de Medicina do ABC (FMABC) , Santo Andre, SP , Brazil.
authors.forename: Renata Claudino
authors.initials: RC
authors.lastname: Rossi
authors.forename: Franciele Marques
authors.initials: FM
authors.lastname: Vanderlei
authors.forename: Aline Fernanda
authors.initials: AF
authors.lastname: Bernardo
authors.forename: Naiara Maria de
authors.initials: NM
authors.lastname: Souza
authors.forename: Ana Clara Campagnolo Real
authors.initials: AC
authors.lastname: Goncalves
authors.forename: Ercy Mara Cipulo
authors.initials: EM
authors.lastname: Ramos
authors.forename: Carlos Marcelo
authors.initials: CM
authors.lastname: Pastre
authors.forename: Luiz Carlos de
authors.initials: LC
authors.lastname: Abreu
authors.forename: Luiz Carlos Marques
authors.initials: LC
authors.lastname: Vanderlei
mesh_terms: D000368:Aged; D001341:Autonomic Nervous System / Q000502:physiology*; D016022:Case-Control Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000534:rehabilitation; D012119:Respiration; D012138:Respiratory Therapy / Q000379:methods